If you got used to JUnit 4′s assertThat with various
matchers (of course you will need junit-dep.jar and hamcrest.jar to get
the full set instead of the small subset integrated in junit.jar), make
sure you don’t overlook the matcher hasProperty. It is very useful if
you have non-trivial objects and cannot use some more flexible language
like Groovy for your unit tests.

The advantage of hasProperty is that it allows you to check a particular property (or more properties with allOf)
of an object while ignoring the others – pretty useful if the object
has 20 properties and checking just one is enough for you. (Admittedly,
an object with 20 properties is an abomination but hey, that’s the real
legacy word!)

Example – check that collection contains two Images with some file names: